The development of planning skills in children is central to most aspects of cognitive development, in that people must plan and monitor the progress of their plans in order to solve cognitive problems. Difficulties in anticipating the consequences of actions are common in the adaptation of children to the problems posed to them by schooling and by the complex activities of our society. Optimal development and successful, healthy adaptation depends on the development of planning skills. In our theoretical approach to the development of children's planning skills planning is conceived as a cognitive skill which is applied opportunistically and pragmatically with the planner relying on information from the immediate environment in constructing a plan. Some or all of the plan may be developed in the course of carrying out a sequence of action. This perspective emphasizes the importance of examining the execution of plans. We regard the development of planning skills to be guided in essential ways by feedback from the social and material environment. Children learn about planning through noting the effectiveness of their own planning attempts and revisions of plans, through observation and instruction, and through adjusting their plans to fit with those of others. The two studies which we propose investigate the influence of feedback from experience and from social interaction on the development of planning skills, and the relation of plans to their execution. Both studies involve children in games requiring efficient planning of spatial routes within time or resource constraints. The studies examine the development of planning skills through ontogenetic comparisons using different age groups and microgenetic comparisons as children learn to plan across episodes of a given task.